1. Field of the Invention
The present invention relates to a print server and printing apparatus, a network printing system, a printing method and, more particularly, to print processing using a print service such as a cloud print service which is provided from a remote server and also to cancel processing thereof.
2. Description of the Related Art
A system in which a cloud print service generates print data in response to a demand from a user terminal, and a printing apparatus receives and processes the print data and executes print processing is known. The cloud print service and printing apparatus are connected via a public communication network that configures the Internet. For this reason, a firewall is normally set between the network to which the printing apparatus belongs and the Internet, and the printing apparatus and cloud print service communicate with each other via the firewall. The firewall normally allows the printing apparatus to send information to the cloud print service, but does not allow the cloud print service to send information to the printing apparatus except for a response to a request from the printing apparatus. That is, an apparatus on the Internet side cannot normally access, as an initiator, a local network having the firewall. This is to restrict accesses from, for example, unspecified computers on the Internet to the local network.
Owing to this restriction, the cloud print service uses a so-called pull-print method. In the pull-print, a cloud print server (to be simply referred to as a server hereinafter) generates print data, and stores the print data in a specific spool on the cloud print service (that is, on the Internet side viewed from the printing apparatus). The printing apparatus monitors the spool on the cloud print service, and detects that new print data is stored. Monitoring is attained by, for example, periodic polling. When the printing apparatus detects that new print data is stored, it sends a print data request to the spool, and receives the print data as a response to that request, thus executing print processing.
A technique for starting print processing by monitoring print data stored in a spool on a server in this way is disclosed in Japanese Patent Laid-Open No. 2004-351806.
When the firewall exists between the server and printing apparatus, since the server cannot serve as an initiator to transmit information to the printing apparatus, if a cancel operation of the print service is made on a user terminal, the user terminal can notify the server of the cancel. However, the server cannot notify the printing apparatus of any cancel. Also, when the user terminal belongs to a network different from that of the printing apparatus, the user terminal cannot notify the printing apparatus of any cancel. For this reason, even when the server cancels generation of print data and sending of the print data to the spool due to the cancel of the print service, the spooled print data is transferred to the printing apparatus, and the print processing of the already spooled print data is executed although it is canceled.
Japanese Patent Laid-Open No. 2004-351806 also discloses a print service cancel implementation method when the firewall exists between the server and printing apparatus.
As described above, when the firewall exists between the cloud print service and printing apparatus, appropriate cancel processing cannot be executed.